Primary Thyroid Lymphoma

Abstract

Primary thyroid lymphoma is a rare cause of both thyroid malignancy and extranodal lymphoma. It should be suspected in patients with a rapidly enlarging neck mass, especially in women with Hashimoto’s thyroiditis. Certain ultrasound features such as enhanced posterior echoes and hypoechogenicity can suggest the diagnosis, but biopsy for confirmation is ultimately needed. With advances in immunophenotypic analysis, fine needle aspiration can be used for diagnosis in the hands of experienced physicians, but open biopsy may be needed for confirmation. The most common type of primary thyroid lymphoma is diffuse large B-cell lymphoma which behaves in a more aggressive manner than mucosa-associated lymphoid tissue (MALT) lymphoma. Radiation therapy can be employed for localized MALT lymphoma, but combination therapy with chemotherapy and radiation is needed for disseminated disease or aggressive histologic subtypes. More recently, addition of the anti-CD20 antibody rituximab to chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone has been successful for treatment of extranodal non-Hodgkin’s lymphomas and provides hope for the treatment of primary thyroid lymphoma.